Steering system for motor vehicles

ABSTRACT

The invention relates to a steering system for motor vehicles, in which the steering spindle part, lying in the steering mechanism housing, is clamped axially in the same end region of the steering spindle part, in which the steering angle sensor unit for sensing the rotational angle or changes in the rotational angle is also provided.

The invention relates to a steering system for motor vehicles, inparticular a rack and pinion steering system for automobiles.

Steering systems of the abovementioned type are known from DE 197 03 903A1. In these known steering systems, a steering wheel as provided assteering input means for the driver, and the steering commands input bythe driver are transmitted via a steering mechanism, having a steeringspindle part configured as a pinion, to steering linkages which lead tothe wheels to be steered and are connected to the rack which meshes withthe pinion. The steering spindle part, which is part of the steeringmechanism and is mounted in the steering mechanism housing, is connectedto the steering wheel mechanically in the known solution. The steeringspindle part, which comprises the pinion, is mounted in the steeringhousing on both sides of the pinion, the input-side mounting beingformed by a roller bearing which axially supports the steering spindlepart and is fixed in position relative to the steering mechanism housingby a clamping body which can be screwed in relative to said steeringmechanism housing. At the opposite end from the axially supportingmounting, the steering spindle part which forms the pinion ends in aclosed space of the mechanism housing and bears a permanent magnet, towhich permanent magnet a stationary sensor which is sensitive tomagnetic fields is assigned on the outside of the housing, said sensorbeing protected and held by a sensor carrier which can be plugged ontothe steering mechanism housing in the manner of a cover.

The location of the steering angle sensor unit and the axial support ofthe steering spindle part, which is held in the steering mechanismhousing, at opposite ends of the steering mechanism housing restrictsthe constructional possibilities, in particular also with regard to ascompact as possible a construction of the steering mechanism, and can bedisadvantageous even in terms of installation and cost considerations.

Furthermore, it is known in practise to fix rack and pinion steeringsystems in position in the steering mechanism housing at its end whichlies opposite the input side, relative to the spindle part located insaid steering mechanism housing, by means of a roller mounting which isclamped in axially.

The invention is based on the object of configuring a steering systemfor motor vehicles of the type mentioned in the introduction, such thatthe result is a particularly simple and inexpensive construction, whichis distinguished by advantageous possible ways of being connected to thesteering input means, in particular also in conjunction with steeringsystems which operate using electric power assistance or using electrictransmission (steer by wire) of the commands which are imparted by thedriver via the steering input means.

A steering system in accordance with the invention is configured inaccordance with the features of claim 1 and distinguished by the factthat the radially and axially guiding roller mounting and the steeringangle sensor unit for detecting the rotational angle or changes in therotational angle at the steering wheel (as steering input means) areassigned to the same end, namely that end of the steering mechanismhousing which is remote from the steering input means, this solutionbeing combined with the steering angle sensor being held and insertedradially with respect to the mounting, which permits a shorterconstruction and also provides favorable preconditions for integratingthe permanent magnet into elements which are already present. Inparticular, a solution of this type can also have advantages with regardto varying the installation positions of the sensor unit, as theaccessibility of the sensor, which is the more critical part of thesteering shaft sensor unit in terms of maintenance considerations, isnot governed by the axial accessibility of the steering mechanism, whichproves to be advantageous as the possibilities of varying thepositioning of the steering mechanism, and the spatial conditions inrelation to this, are frequently critical.

In conjunction with the axial clamping in of the roller bearing, whichtakes place according to the invention in a simple way by means of aspacer sleeve in conjunction with a clamping body, said clamping bodypreferably being configured as a cover part and therefore at the sametime sealing and closing off the end of the steering mechanism housingaxially, it is possible to configure the steering mechanism housing tobe open at both ends, preferably in the axial direction, which isadvantageous for production, and the steering spindle part, lying in thehousing, is clamped simply with respect to the inner ring of the rollerbearing, the latter being clamped axially with respect to the housing bymeans of the outer ring, the corresponding screw connection beingpossible using the open end of the steering mechanism housing, saidscrew connection being closed by the cover. Optionally, the steeringspindle part, lying in the steering mechanism housing, can be insertedinto the steering housing in a preassembled state together with thebearing, and it is subsequently possible to clamp in the bearing bymeans of the spacer sleeve and the cover part. In conjunction with thescrew connection of the steering spindle part with respect to the innerring of the axially supporting bearing, it proves expedient to configurethe corresponding threaded nut with a necklike extension, approximatelycomparable with a castle nut, and to configure the necklike extension asa holder for the permanent magnet, so that special fastening means areobviated.

In conjunction with such a refinement, it is possible for the associatedsensor to be configured as the end of the corresponding holding space,given a flat configuration between the permanent magnets and the cover,it being intended for the sensor carrier to be inserted laterally and itbeing possible for the spacer sleeve to pass through in a leadthroughwhich can have large tolerances, with simultaneous guidance and sealingbetween the sensor carrier and the radial holding bore for the sensorcarrier in the steering mechanism housing. This pinlike part of thesensor carrier is expediently coupled to a base plate, which can alsosimultaneously serve as a carrier for the electronic switching andevaluation units of the sensor unit and can be fixed in position in asimple manner relative to a supporting surface of the steering mechanismhousing, so that simple installation conditions result and the sensorunit can also optionally be replaced in its entirety withoutdifficulties.

In order to make installation easier, it can be of advantage,furthermore, to fix the spacer sleeve in terms of its rotationalposition relative to the holding space by means of a correspondingsliding guide, having large tolerances, or the like, so that theleadthrough provided in the spacer sleeve is positively aligned with thecorresponding bore in the housing of the steering mechanism duringinstallation of the spacer sleeve.

Further details and features of the invention emerge from the claims.Furthermore, the invention is explained with further details in thefollowing text using the drawing, said drawing showing a diagrammaticsection through a steering mechanism, a steering angle sensor unit beingassigned to the latter.

BRIEF DESCRIPTION OF THE DRAWINGS

The single drawing shows a diagrammatic section through a steeringmechanism according to one embodiment of the invention.

The steering mechanism shown in the diagram is a component part of arack and pinion steering system for automobiles and is not shown interms of its connection to the steering wheel as a steering input meansactuated by the driver. The parts of the steering system which arerelevant to said connection are not the subject matter of the invention,and can be configured, for example, in accordance with DE 197 03 903 A1,FIG. 1, the connection between the steering wheel and steering mechanismbeing mechanical and comprising a steering spindle which ends in asteering spindle part 1 at the steering mechanism end, said steeringspindle part 1 being configured as a pinion meshing with a rack 2 andbeing mounted on both sides of the pinion toothing 3 in the housing 4 ofthe steering mechanism denoted overall by 5. An in particular electricactuating drive can be contained (not shown) in the connection to thesteering input means (likewise not shown), said actuating drive, as aservomotor actuating drive, assisting steering forces introduced via thesteering input means or, in the context of a steer by wire steeringsystem, converting the steering forces, which are introduced via thesteering input means and transmitted by means of corresponding actuatingsignals, into corresponding steering forces. A possible torquetransmitting connection to the steering spindle part 1 is indicated at6.

The steering spindle part 1, which is configured as a pinion, isassigned mountings 7, 8 in the housing 4 on both sides of the piniontoothing 3, of which the mounting 7 on the input side is formed by aneedle bearing and the mounting 8 at the end is formed by a rollerbearing which is depicted as a ball bearing and by means of which thesteering spindle part 1 is axially fixed in the housing 4. For thispurpose, the outer ring 9 of the roller bearing, which forms themounting 8, is clamped against a housing shoulder 10 by means of aspacer sleeve 11, the latter being acted on by a cover 12 which isinserted, as a screw cover, into the throughhole, which forms the holderfor the steering spindle part, at the end remote from the input end,i.e. the end adjacent to the steering input means, of the steeringmechanism housing 4.

The spacer sleeve 11 bridges a housing space 13, in which the nut 14lies, the steering spindle part 1 being clamped against the inner ring15 of the bearing 8 by means of said nut 14, the nut 14 being screwedonto the journal 16, which ends in the housing space 12, of the steeringspindle part 1.

In the exemplary embodiment, the nut 14 is provided, in the manner of acap nut, with a necklike extension 17, which projects beyond the end ofthe journal 16 and is configured as a holder for a permanent magnet 18,which lies in the housing space 13 in the case of a mounting 8 clampedaxially against the steering mechanism housing 4 by means of the cover12, specifically at a distance from the cover 12 which allows a sensor19 which is sensitive to magnetic fields to be arranged between thecover 12 and magnet 18, said sensor 19 being configured, by way ofexample and preferably, as a Hall sensor. The sensor 19 is held in itsposition overlapping the magnet 18 by means of a sensor carrier 20 whichcomprises a plug-in pin 21 and a support plate 22 connected to theplug-in pin 21. The plug-in pin 21 passes through the steering spindlehousing 4 radially in a matching bore 24 which is sealed off, forexample, by means of the indicated annular seal 23 and lies congruentlywith a corresponding, radial leadthrough 25 in the spacer sleeve 11.Said leadthrough 25 can be correspondingly overdimensioned relative tothe plug-in pin 21, i.e. have large tolerances, and, with regard tomaking installation easier, it can be expedient to align the spacersleeve 11, in relation to its leadthrough 25, on the bore 24 by means ofa corresponding guide (not shown).

The support plate 22 is preferably clamped against a bearing surface 27of the housing 4 by means of a screw connection 26 and is configured,for example, as a holder for further components, in particularcomponents of an electronic unit connected downstream of the sensor 19.

The radial insertion and holding of the sensor 19 leads to a design ofthe steering mechanism 5 which is very compact in terms of length, thetype of holding device for the permanent magnet 18 further simplifyingthe design and, in conjunction with the radial insertion and holding ofthe sensor 19, different installation positions being possible relativeto the periphery of the housing 4, which permits good possibilities foradaptation to the respective structural conditions specific to thevehicle.

In a known manner, the rack 2 is clamped and supported in sprung fashionagainst the steering spindle part 1 (as shown at 28), the relevantdomelike holder 29 forming no obstacle to arranging the sensor carrier20 in the corresponding peripheral region of the housing 4, if thesupport plate 27 of said sensor carrier 20 is aligned or adapted.

1. A steering system for motor vehicles, in particular a rack and pinionsteering system for automobiles, having a steering input means on thevehicle side, and a steering spindle part which is coupled to thesteering input means, lies in a steering mechanism housing and ismounted on both sides with respect to the steering mechanism housing,one of the mounting being configured as a roller bearing which isclamped in axially with respect to the steering mechanism housing, apermanent magnet arranged at said steering spindle part which ends in aclosed space of the steering mechanism housing, a stationary sensorwhich is sensitive to magnetic fields arranged opposite the permanentmagnet and having an assigned sensor carrier which is to be connected onthe outside to the steering mechanism housing, a roller bearing mountingwhich is axially clamped in provided at an end region, which bears thepermanent magnet, of the steering spindle part and is fixed in positionby means of a spacer sleeve, which, as an extension of the steeringspindle part, is acted on axially by a cover, which closes the end ofthe housing chamber, said spacer sleeve having a radial leadthrough forthe sensor carrier located radially to the sensor.
 2. The steeringsystem as claimed in claim 1, wherein the spacer sleeve is formed by aplug-in sleeve.
 3. The steering system as claimed in claim 1 or 2,wherein the cover is screwed into a threaded region of the housingchamber.
 4. The steering system as claimed in claim 1 or 2, wherein theradial leadthrough of the spacer sleeve is configured as a bore.
 5. Thesteering system as claimed in claim 4, wherein the spacer sleeve to thesteering mechanism housing is assigned a rotational securing means. 6.The steering system as claimed in claim 4, wherein the sensor carrierhas a plug-in pin, which is held in a guide bore, corresponding to theleadthrough of the spacer sleeve, of the steering mechanism housing. 7.The steering system as claimed in claim 6, wherein the plug-in pin isarranged on a support plate.
 8. The steering system as claimed in claim7, wherein the support plate is assigned switching and/or evaluationelectronics for the steering angle sensor.
 9. The steering system asclaimed in claim 8, wherein it is possible to clamp the support plateagainst a support surface of the steering mechanism housing.
 10. Thesteering system as claimed in claim 1 or 2, wherein the cover and thespacer sleeve form a clamping unit which is configured, in particular,as an installation unit.